Telephone station circuit



Nov. 14, 1933. v w, c. PHEBUS 1,934,736

TELEPHONE STAT ION CIRCUIT Filed May 12, 1932 In't'En' h: r Lnliuiam 1:. Phabus Patented Nov. 14, 1933 TELEPHONE STATION CIRCUIT William C. Phebus, Iark Ridge, Ill., assignor, by mesne assignments, to Associated Electric Laboratories, Inc., Chicago, III., a corporation of Delaware Application May 12, 1932. Serial No.,6l0,893

10 Claims.

The present invention relates to telephone systems in general, but, more particularly to train dispatching and similar systems in which a large number of waystations are bridged across 5 a common line of considerable length.

The principal object of the present invention is to provide an improved arrangement of the waystat ion circuits whereby the proper transformer ratios most suitable for great efiiciency in 1 reception and transmission are obtained.

This and other objects of the present invention will be more readily understood by reference to the following detailed description and the associated drawing in which is diagrammatically represented a telephone line with two Waystations bridged thereacross.

Referring to the drawing, conductors 1 and 2 represent a' pair of conductors constituting a telephone line common to all of the waystations of the system, two of which are represented at A and B. Each of the stations A and B, as well as every other waystation of the system, is associated with the line through the transformer 3 bridged across the line. Each of the transform- 25 ers 3 has four windings 4, 5, 6, and 7, thetwo windings 4-. and 5 being connected in the bridge across the line and the other windings 6 and '7 being connected in circuits inductively associated with the bridge circuit. A condenser 10 is included in each bridge circuit to prevent the passage of direct current across the bridge. This arrangement is suitable if the line is provided with selectors in order to prevent the loss, of selector current, or if the line is used for telegraphic transmission, but, the condensers may be omitted if the line is used solelyfor telephonic transmission. I V

Each waystation is provided with a'receiver 8,

a transmitter 9, a receiver switch 11; a battery 40 12, and a transmission key comprising springs 13, 14, and 15 and their associated contacts. The circuit of station B has been shown in listening condition, that is, with the key in its normal position, while the circuit of station A has been shown in talking condition, that is, with the key in the operated position.

Assuming the receiver switch 11 of the circuit of station B is closed, the receiver is normally included in a circuit extending through the receiver 8, receiver switch 11, transformer winding 6, and key spring 13 and its normally engaged contact. Under these conditions, the bridge includes the condenser 10, "transformer winding 4, spring 14 and its normally engaged contact, and transformer winding 5. -In other words, the transformer windings 4 and 5 are connected in series in the bridge whenthe circuit is conditioned for listening. The transformer windings constitute the proper number of turns to provide the proper transformer ratio so conducive to proper receiving efilciency and to provide the correct predetermined impedance for the station to obtain satisfactory transmis sion eliiciency throughout the entire system.

The ratio of transformation of the transformer 3 is changed from that used for receiving only to that more suitable for transmission by the operation of the transmission key to the position shown in. the circuit of station A. Under these conditions, the transmitter is connected in circuit with the transformer winding 7 and battery 12 at key spring 13 and its alternate contact and theres'istance element 16 is included in circuit with the-receiver to avoid disagreeable disturbances in the receiver during transmission.

At key spring 14, the series circuit of the two transformer windings 4 and 5 is opened; while, at the-alternate contact. of spring 1 and at spring .15 and its contact, the transformer windings iand 5 are included in the bridge in parallel, thereby altering the ratio of transformationandv the impedance 'of the transformer to obtain the maximum transmission efficiency of the waystation. f u

To prevent undue loss of energy during trans- S5 mission when the transformer windings ,4 and 5- arevconnected in parallel in the bridge, those windings are made ofequal numbers of-turns of wire. The, transformer winding 6 is made of such a number of turns as to obtain the proper receiving-ratio of transformation with the-windings 4 and" 5 in series; while the winding '7 constitutes the number of turns necessary to obtain the propertransmission ratio of transformation withthe transformerwindings and 5 in-parallel.. f

- By the'present method of switching, the normallyv high impedance bridge, which. ispresent at each Waystation regardless of whether or not the receiver is associated. with the line, is changed to a low impedance bridge for transmission while, at the same time, the transmitter is connected in a circuit conductively separate from the re-- ceiver circuit, and an additional amount of resistance is included in series with the receiver. This arrangement of the transmitter and receiver circuits provides a low impedance transmission circuit and a'recei'vin'g circuit high in butt-in eificiency and sufiiciently anti-side tone to avoid disagreeable clicks in the receiver during transmission and to be satisfactory for all practical purposes.

The invention having been thus described, what is considered new and is desired to have protected by Letters Patent is pointed out in the claims which follow.

What is claimed is:

1. A telephone station circuit comprising a pair of conductors, a transformer having a plurality of windings inductively associated, a bridge circuit extending between said conductors and including certain ones of said windings connect ed in series, a receiver, a transmitter, a source of current, a second circuit includingsaid receiver and another one of said windings, and means for simultaneously connecting said certain windings in parallel in said bridge circuit and completing a third circuit including said transmitter, said source of current, and still another one of said. windings.

2. A telephone station circuit comprising a pair of conductors, a transformer having a plurality of windings inductively associated, a bridge circuit extending between said conductors and including certain ones of said windings normally connected in series; a transmitter, a source of current, and means for simultaneously connecting said certain windings in parallel in said bridge circuit and completing a second circuit including said transmitter, said source of current and another one of said windings.

3. A telephone station circuit comprising a pair of conductors, a transformer having a pluralityof windings inductively associated, a bridge circuit extending between said conductors and including certain ones of said windings connected in series, a receiver, a transmitter, a resistance element, a source of current, a second circuit including said receiver, said resistance element and another one of said windings, means for simultaneously connecting said certain windings parallel in said bridge circuit, and completing a third circuit including said transmitter, said source of current, and still another one of said windings.

4. A telephone station circuit comprising a pair of conductors, a transformer having a plurality of windings inductively associated, a bridge circuit extending between said conductorsand including certain ones of said windings normally connected in series, a receiver, a transmitter, a

source of current, a second circuit including said receiver and another one'of said windings, meansfor completing a third circuit including said transmitter, said source of current and still another one of said windings, and means for altering the series connection of said certain windings in said bridge circuit to parallel connections upon said completion of said third circuit.

5. A telephone station circuit comprising a pair of conductors, a transformer having four wind-'- ings, a bridge circuit extending between said conductors and including two of said windings normally connected in series, a receiver, a transmitter, a source of current, a second circuit including said receiver and the third winding of said transformer, and means for simultaneously connecting said two windings in parallel in said bridge circuit and completing a third circuit including said transmitter, said source of current and the fourth of. said windings, whereby said transmitter and said receiver are operatively associated with said line by separate inductive circuits and whereby the ratio of transformation is altered upon the completion of the transmitter circuit.

6. A telephone station circuit comprising a pair of conductors, a transformer having a phi-'- rality of windings inductively associated, a bridge circuit extending between said conductors and including certain ones of said windings connected in series, a receiver, a resistance element, a transmitter, a source of current, a second circuit including said receiver, said resistance element and another one of said windings, means for completing a third circuit including said transmitter, said source of current and still another one of said windings, and means for connecting said certain windings in parallel in said bridge circuit upon said completion of the third circuit.

7, A telephone station circuit comprising a pair of conductors, a transformer having a plurality of windings inductively associated, a bridge circuit extending between said conductors and including certain ones of said windings in parallel, a receiver, a transmitter, a source of current, a second circuit including the receiver and another one of said windings, and switching means for completing a third circuit including the transmitter, the source of current and still another one of said windings and simultaneously therewith, altering the connection of said certain windings in said bridge circuit, whereby diiferent ratios of transformation for reception and transmission are obtained.

,8. A telephone station circuit comprising a pair of conductors, a transformer having a plurality of windings inductively associated, a bridge circuit extending between said conductors and including certain ones of said windings, a receiver, a transmitter, a source of current, a second circuit including the receiver and another one of said windings, and switching means for simultaneously completing a third circuit which is independent of said second circuit and which includes the transmitter, the source of current and still another one of said windings, and altering the connection of said certain windings in said bridge circuit and at the same time maintaining all of said certain windings in said bridge circuit, whereby difierent ratios of transformation for reception and transmission are obtained without 1 omitting any portion of said certain windings.

9. A telephone station circuit comprising a pair of conductors, a transformer having a plurality of windings inductively associated, a bridge circuit extending between said conductors and including certain ones of said windings connected in series, a receiver, a transmitter, a source of current, a second circuit including said receiver and another one of said windings, and means. for

simultaneously connecting said certain windings i in parallel in said bridge circuit, modifying the conductivity of said second circuit, and completing a third circuit including said transmitter, said source of current, and still another one of said windings.-

10. In a telephone station circuit comprising a pair of conductors, a transformer having a plurality of windings inductively associated, a bridge circuit extending between said conductors and including certain ones of said windings connected in series, a receiver, a transmitter, a resistance element, a second circuit including said receiver, said resistance element, and another one of said windings, a normally closed shunt path about said resistance element; and means for connecting said certain windings in parallel in said bridge circuit, opening said shunt path, and completing a third circuit including said transmitter, said source of current, and still another one of said windings. 7 WILLIAM C. PHEBUS. 

